Rotary electric machine having winding coils with first and second portions connected in series

ABSTRACT

A rotary electric machine includes a stator extending along an axis and having teeth arranged about the axis. The teeth are circumferentially spaced apart by slots. Winding coils extend around the teeth and through the slots. The winding coils are electrically connected to one another to form phases. At least one of the winding coils has a first portion extending through first and second slots of the slots and including first end turns extending between the first and second slots over an axial end surface of the teeth. A second portion extends through the first and second slots and includes second end turns extending between the first and second slots over the axial end surface of the teeth. The first and second portions are connected in series at a third end turn spaced closer to the axial end surface than either the first or second end turns.

TECHNICAL FIELD

The present invention relates generally to rotary electric machines, andspecifically to a winding configuration for rotary electric machines.

BACKGROUND

All electric motors and generators, i.e., rotary electric machines,generate heat during operation. The heat can be removed using a fluidsuch as air or a liquid. In some examples, the cooling structure isprovided in the slot to provide more direct contact with the windingcoils and thereby more effectively remove heat generated therefrom. Withthis in mind, it is desirable to interconnect the winding coils in amanner that minimizes electrical and/or thermal resistance therethrough.

SUMMARY

In one example, a rotary electric machine includes a stator extendingalong an axis and having teeth arranged about the axis. The teeth arecircumferentially spaced apart by slots. Winding coils extend around theteeth and through the slots. The winding coils are electricallyconnected to one another to form phases. At least one of the windingcoils has a first portion extending through first and second slots ofthe slots and including first end turns extending between the first andsecond slots over an axial end surface of the teeth. A second portionextends through the first and second slots and includes second end turnsextending between the first and second slots over the axial end surfaceof the teeth. The first and second portions are connected in series at ajoint on an end turn spaced an axial distance closer to the axial endsurface than either the first or second end turns.

In another example, a winding coil is provided for a rotary electricmachine having a stator extending along an axis and having teetharranged about the axis. The teeth are circumferentially spaced apart byslots. The winding coil has a first portion for extending through firstand second slots of the slots and including first end turns extendingbetween the first and second slots over an axial end surface of theteeth. A second portion is provided for extending through the first andsecond slots and includes second end turns extending between the firstand second slots over the axial end surface of the teeth. The first andsecond portions are connected in series at a joint on an end turn spacedan axial distance closer to the axial end surface than either the firstor second end turns.

In another example, a rotary electric machine includes a statorextending along an axis and having teeth arranged about the axis. Theteeth are circumferentially spaced apart by slots. Winding coils extendaround the teeth and through the slots. The winding coils areelectrically connected to one another to form phases. Each winding coilincludes first and second form-wound diamond coil portions connectedend-to-end in series with one another. Each slot receives a pair offirst portions and a pair of second portions.

In another example, a rotary electric machine includes a statorextending along an axis and having teeth arranged about the axis. Theteeth are circumferentially spaced apart by slots. First and secondwinding coils extend around the teeth and through the slots. The firstand second winding coils are electrically connected to one another toform phases. The first and second winding coils extends through firstand second slots of the slots such that successive turns of the firstwinding coil in the first slot are wound in a first radial direction andsuccessive turns of the second winding coil in the first slot are woundin a second radial direction opposite the first radial direction.

In another example, a rotary electric machine includes a statorextending along an axis and having teeth arranged about the axis. Theteeth are circumferentially spaced apart by slots. Winding coils extendaround the teeth and through the slots. The winding coils areelectrically connected to one another to form phases. At least one ofthe winding coils has a first portion extending through first and secondslots of the slots and first end turns extending between the first andsecond slots over an axial end surface of the teeth. A second portionextends through the first and second slots and includes second end turnsextending between the first and second slots over the axial end surfaceof the teeth. The first and second portions are connected in series. Inthe first slot successive turns of the first portion are wound in afirst radial direction and successive turns of the second portion arewound in a second radial direction opposite the first radial direction.

Other objects and advantages and a fuller understanding of the inventionwill be had from the following detailed description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a rotary electric machine having an examplestator winding coil.

FIG. 2 is a section view of the rotary electric machine taken alonglines 2-2 of FIG. 1 and including a rotor.

FIG. 3 is a front view of one of the winding coils of FIG. 1 .

FIG. 4 is a schematic illustration of an example winding coilconfiguration for the stator.

FIG. 5 is a schematic illustration of a winding coil extending aroundteeth of the stator.

FIG. 6 is a schematic illustration of another example winding coilconfiguration.

FIG. 7 is a schematic illustration of another example winding coilconfiguration.

DETAILED DESCRIPTION

The present invention relates generally to rotary electric machines, andspecifically to a winding configuration for rotary electric machines.Referring to FIGS. 1-2 , one example rotary electric machine 20 includesa rotor assembly 40 rotatable within and relative to a stationary stator30. A plurality of permanent magnets 24 a. 24 b are secured to theperiphery of a back iron of the rotor assembly 40. The magnets 24 a, 24b and back iron are rotatable together about a central axis 24 of themachine.

The stator 30 extends about and along the axis 24. The stator 30includes a ring-shaped core 32 formed from stacked laminations. Teeth 34extend radially inward from the core 32 towards the axis 24. Each tooth34 extends from a first axial end surface 35 to a second axial endsurface 37 (see FIG. 5 ). The teeth 34 are arranged circumferentiallyabout the axis 24 and extend substantially the entire length of thestator 30. The core 32 and teeth 34 can be formed from an electricallyconductive material, such as laminated silicon steel.

Each tooth 34 includes a hook-shaped, resilient tab 41 for securing thetooth to the core 32. In particular, each tab 41 extends into an openingor slot in the core (not shown). A corresponding wedge 43 is insertedbetween a portion of the core 32 and the tab 41 to deflect the taboutward into engagement with the core in a manner that prevents relativeaxial and radial movement between the tooth 34 and the core. The wedge43 urges the tab 41 radially outward to pull the tooth 34 radiallyoutward into biased engagement with the core 32 along interface surfaces44 a, 44 b on opposite sides of the tab. Each tooth 34 is secured to thecore 32 in the same manner. Alternatively, the teeth 34 can beintegrally formed with the core 32 (not shown). Regardless, the teeth 34are circumferentially spaced apart from one another by slots 46.

An optional cooling device 52 can be provided in each slot 46. Eachcooling device 52 includes a cooling bar 54 extending the entire axiallength of the slot 46 between each pair of adjacent teeth 34. In otherwords, the cooling bars 54 are the same—or substantially the same—axiallength as the teeth 34. Each cooling bar 54 includes a pair of fluidpassageways 56 a. 56 b and a tab 58. It will be appreciated that thecooling bar 54 could include more or fewer fluid passageways. In anycase, the tab 58 supports the fluid passageways 56 a. 56 b and extendsradially outward towards the stator core 32.

Each cooling bar 54 is surrounded by a thermal interface material orlayer 59 formed from, for example, a silicon-based material. Inoperation, a cooling fluid flows in one direction through the fluidpassageways 56 a and in the opposite direction through the fluidpassageway 56 b to help remove heat from the winding coils 60. A moredetailed description of the cooling device 52 can be found in U.S.Publication No. 2017/0194838, the entirety of which is incorporated byreference herein.

Winding coils 40 formed from one or more winding turns of electricallyconductive material such as copper, are wound around the teeth 34 andpass through the slots 46 on opposite sides of the cooling devices 52(when present). In one example, the winding coils 60 are wound in a3-phase configuration such that a portion of the winding coils are inphase A, a portion of the winding coils are in phase B. and a portion ofthe winding coils are in phase C. Each phase receives the same orsubstantially the same amount of current. Other phase configurations arecontemplated. Multiple winding coils 60 can be connected in seriesand/or parallel and still receive the same amount of current. In a3-phase configuration, phases can be connected in either a wye or deltaconfiguration.

The winding coils 60 are made from rectangular wire formed into adiamond shape as shown in FIG. 3 . Each winding coil 60 includes a firstportion 70 and a second portion 80 electrically connected together at aconnection or joint 88. That said, the first and second portions 70, 80can each constitute a form-wound diamond coil portion. In any case, thefirst and second portions 70, 80 can be physically connected to oneanother in an end-to-end manner by electrical splicing, which can beaccomplished by, for example, a brazed connection, a welded connection,a solid state welded connection, a soldered connection, a crimpedconnection, a screw terminal and/or a spring terminal.

The first portion 70 includes straight sections 72 and end turns 74connecting the straight sections. The second portion 80 includesstraight sections 82 and end turns 84 connecting the straight sections.The straight sections 72, 82 extend generally parallel to one anotherthrough the slots 46. i.e., on opposing sides of one or more teeth 34.The end turns 74, 84 extend generally parallel to one another betweenslots 46, i.e., over one or more teeth 34.

The winding coils 60 can be wound onto the stator 30 in any number ofknown manners, e.g., concentrated wound, distributed wound or hairpinwound. As shown, the winding coils 60 are formed from rectangular wirebent into a diamond shape and distributed wound around two teeth 34 and,thus, the winding coils span three slots 46 (identified at 46 a, 46 b,and 46 c for clarity). Extending the winding coils 60 around more orfewer teeth 34 is contemplated.

The winding coils 60 are oriented in the slot 46 such that incross-section the length (the longer dimension) extends generallycircumferentially about the axis 24. The width (the smaller dimension)extends radially towards the axis 24. Multiple winding coils 60 in thesame slot 46 are arranged abutting or adjacent one another in the radialdirection and abutting or adjacent the associated tooth or teeth 34.

The first and second portions 70, 80 are wound around the teeth 34 suchthat the straight sections 72 and 82 form respective wire groups orbundles 76 and 86, respectively, within the slots 46. The examplewinding coils 60 shown includes six turns each of the first and secondportions 70, 80 and, thus, the bundles 76, 86 in this example aredivided into groups of three turns. Consequently, for each winding coil60 a wire bundle 76 of three straight sections 72 and a wire bundle 86of three straight sections 82 are provided in the first slot 46 a.Similarly, a wire bundle 76 of three straight sections 72 and a wirebundle 86 of three straight sections 82 are provided in the third slot46 c.

The straight sections 72 within each wire bundle 76 are stacked in acolumn in the radial direction. The straight sections 82 within eachwire bundle 86 are stacked in a column in the radial direction. The wirebundles 76, 86 within the first slot 46 a are positioned on oppositesides of the associated cooling device 52 in the circumferentialdirection. The wire bundles 76, 86 within the third slot 46 c arepositioned on opposite sides of the associated cooling device 52 in thecircumferential direction.

The wire bundles 76, 86 can be physically separated from the coolingdevices 52 by the thermal interface material 59. The winding coils 60can be electrically insulated from the teeth 34 and stator core 32 byslot liners 64 formed from, for example, polyimide tape or nomex paper,which add to the electrical insulation on the wires. Consequently, eachwire bundle 76, 86 in each slot 46 is circumferentially sandwichedbetween the thermal interface material 59 and the slot liner 64.

It will be appreciated, however, that the cooling device 52 can beomitted (see FIG. 6 ) in which case the wire bundles 76, 86 are stillprovided on opposite circumferential sides of the slot 46. The wirebundles 76, 86 in this construction can abut one another or be spacedcircumferentially from one another.

When another winding coil 60 is provided in the same slot 46, thebundles 76 in the same slot are stacked in the radial direction. Bundles86 of different winding coils 60 within the same slot 46 are alsostacked radially. A circumferential centerline or dividing line 68extends through all the teeth 34 and between the bundles 76, 86associated with one winding coil 60 and the bundles associated withanother winding coil in the same slot 46. The dividing line 68 alsoextends radially between the bundles 76 of a winding coil 60 in one slot46 and the bundle 76 of the same winding coil in another slot. The sameis true of the bundles 86 of the same winding coil 60.

FIG. 4 illustrates one example winding configuration of the windingcoils 60 around the teeth 34. Although four teeth 34 are shown it willbe appreciated that this winding configuration is the same for theremaining teeth in the stator 30. To this end, the winding configurationis applicable to a stator 30 having M number of slots 46 anddouble-layer winding coils. The teeth 34 and slots 46 are given thesuffix “a”. “b”, “c” . . . “M” to refer to the first tooth, secondtooth. M^(thp) tooth, etc. for purposes of clarity.

A legend 90 is provided for facilitating understanding of the wiringconfiguration. Reference number 92 indicates the winding coil number,e.g., 1^(st), 2^(nd), 3^(rd) . . . M^(th). Reference number 94 indicatesthe direction of current flow through the wire, with “in” referring to adirection flowing away from the axial end surface 35 (towards the axialend surface 37) and “out” referring to a direction flowing towards theaxial end surface 35 (away from the axial end surface 37). Referencenumber 96 indicates the straight section 72 or 82 of the respectiveportion 70 or 80. Reference number 98 indicates the turn number of theparticular winding portion 70, 80—the 1^(st), 2^(nd) or 3^(rd) in theexample shown.

As noted, each of the portions 70, 80 includes six turns that span threeslots 46 a, 46 b. 46 c and, thus, each portion 70, 80 loops around thefirst and second teeth 34 a. 34 b. Each slot 46 a. 46 c thereforereceives a total of twelve straight sections 72, 82 of the firstwinding. Alternatively, each straight section 72, 82 shown couldrepresent multiple conductors, e.g., two in-hand, connected electricallyin parallel at the end of the winding coil 60. Regardless, although thefollowing description relates to the first winding coil 60 it will beappreciated that subsequent winding coils are wound around thecorresponding teeth 34 in a similar manner.

The first winding coil enters the top (the radially innermost portion)of the first slot 46 a and returns from the bottom (the radiallyoutermost portion) of the third slot 46 c via one of the end turns 74.Subsequent turns in the first winding coil 60 likewise extend betweenthe first and third slots 46 a, 46 c. Successive straight sections 72 inthe first slot 46 a are positioned radially outward of the previousstraight section 72. Successive straight sections 72 in the third slot46 c are positioned radially inward of the previous straight section 72.In other words, the first portion 70 spirals incrementally towards thedividing line 68.

Successive straight sections 82 in the first slot 46 a are positionedradially inward of the previous straight section 82. Successive straightsections 82 in the third slot 46 c are positioned radially outward ofthe previous straight section 82. In other words, the second portion 80spirals incrementally away from the dividing line 68. Consequently,current flows (indicated by the arrow F) through the first portion 70towards the dividing line 68 in both slots 46 a, 46 c. In other words,as the current flows into and out of the slots 46 its radial positionwithin the slots is also changing for both portions 70, 80.

On the other hand, current flows F through the second portion 80 awayfrom the dividing line 68 in both slots 46 a, 46 c while flowing intoand out of the slot. That said, within the same winding coil 60 currentflow F is in opposite radial directions through the bundles 76, 86 inthe same slot 46. It will be appreciated that the portions 70, 80 can bewound such that the current flow F is opposite the directions shown inFIG. 4 .

Referring back to FIG. 5 , the joint 88 between the first and secondwinding portions 70, 80 occurs in the transition between the third turnof the first portion 70 exiting the third slot 46 c and the third turnof the second portion 80 entering the first slot 46 a. Consequently, thejoint 88 interconnects the first and second portions 70, 80. The joint88 is located outside the slots 46 and adjacent the end turns 74, 84.Advantageously, the axial distance d₁ between the joint 88 and the firstaxial end surfaces 35 of the teeth 34 is less than the axial distance d₂between any of the other end turns 74, 84 and either axial end surface35, 37. In other words, the joint 88 is closer to the axial end surface35 than the other ends turns 74, 84 and therefore fits under or betweenall the end turns. That said, the joint 88 is positioned axially betweenthe end turns 74, 84 extending over the axial end surface 35 and the endturns extending over the axial end surface 37. This allows the end turns74, 84 forming the joint 88 to have a shorter distance and lesselectrical resistance than the other end turns.

It will be appreciated that bundles 76, 86 associated with anotherwinding coil 60 within the same slot 46 will be configured such thatcurrent flows F in the opposite radial direction for corresponding orassociated bundles. For example, the bundle 76 in the M−1 winding coilin the first slot 46 a has a current flow F towards the dividing line68. The bundle 86 in the M−1 winding coil in the first slot 46 a has acurrent flow F away from the dividing line 68. The bundle 76 in thethird winding coil in the third slot 46 c has a current flow F towardsthe dividing line 68. The bundle 86 in the third winding coil in thethird slot 46 c has a current flow F away from the dividing line 68.

Another example winding configuration is shown in FIG. 7 . As shown,each winding coil 60 has an odd number of turns, namely, five turns. Inthis construction, the number of slots 46 divided by the coil span (ininteger number of slots) is an even number. Each slot 46 receives tenstraight sections 72, 82 from two different winding coils 60 spanningtwo teeth 34. The first winding coil 60 enters the top of the first slot46 a and returns from the bottom of the third slot 46 c.

In contrast to the winding configuration in FIG. 4 , in FIG. 7 one ofthe bundles 76 or 86 in each winding coil 60 has only two turns. Asshown, the bundles 76 in the third, fourth, M−1, and M^(th) winding coil60 have two turns. The bundles 86 in the first and second winding coils60 have two turns. The remaining bundles 76 or 86 in each winding coil60 have three turns. The straight portions 72, 82 in each winding coil60 are therefore asymmetrically stacked or arranged on each side of thecooling device 52.

More specific to the example shown, the first winding coil 60 bundle 76has three turns while the M−1 winding coil bundle 76 has two turns.Similarly, the first winding coil 60 bundle 86 has two turns while theM−1 winding coil bundle 86 has three turns. This winding coil 60configuration can be generalized to any number of slots 46 and coil spanas long as the number of slots divided by the coil span is an evennumber. If this condition is met, this winding configuration allows anodd number of turns for each coil.

In FIG. 7 , the joint 88 between the first and second winding portions70, 80 occurs in the transition between the third turn of the firstportion 70 exiting the third slot 46 c and the third turn of the secondportion 80 entering the first slot 46 a. The joint 88 between bundles76, 86 in each winding coil 60 the joint 88 fits under or between allthe end turns 74, 84, which allows the end turns 74, 84 forming thejoint 88 to have a shorter distance and less electrical resistance thanthe other end turns. In other words, the axial distance d₁ between theend turn 74, 84 having joint 88 and the first axial end surfaces 35 ofthe respective teeth 34 is less than the axial distance d₂ between anyof the other end turns 74, 84 and either axial end surface 35, 37. Thatsaid, the joint 88 is positioned axially between the end turns 74, 84extending over the axial end surface 35 and the end turns extending overthe axial end surface 37.

What have been described above are examples of the present invention. Itis, of course, not possible to describe every conceivable combination ofcomponents or methodologies for purposes of describing the presentinvention, but one of ordinary skill in the art will recognize that manyfurther combinations and permutations of the present invention arepossible. Accordingly, the present invention is intended to embrace allsuch alterations, modifications and variations that fall within thespirit and scope of the appended claims.

1. A rotary electric machine comprising: a stator extending along anaxis and having teeth arranged about the axis, the teeth beingcircumferentially spaced apart by slots; and winding coils extendingaround the teeth and through the slots, the winding coils beingelectrically connected to one another to form phases, at least one ofthe winding coils having: a first portion extending through first andsecond slots of the slots and including: first end turns extendingbetween the first and second slots over an axial end surface of theteeth; and a first joint end turn contiguous with the first end turns;and a second portion extending through the first and second slots andincluding: second end turns extending between the first and second slotsover the axial end surface of the teeth, and a second joint end turncontiguous with the second end turns; the first joint end turn and thesecond joint end turn being connected in series at a joint wherein thefirst joint end turn and the second joint end turn are spaced an axialdistance closer to the axial end surface than either the first or secondend turns.
 2. The rotary electric machine recited in claim 1, wherein inthe first slot successive turns of the first portion are wound in afirst radial direction and successive turns of the second portion arewound in a second radial direction opposite the first radial direction.3. The rotary electric machine recited in claim 2, wherein in the secondslot successive turns of the first portion are wound in the secondradial direction and successive turns of the second portion are wound inthe first radial direction.
 4. The rotary electric machine recited inclaim 1, wherein the winding coils are form-wound diamond coils.
 5. Therotary electric machine recited in claim 1, further comprising coolingdevices positioned in the first and second slots, each cooling devicebeing positioned circumferentially between the first and second portionsof the winding coil of the respective first and second slot.
 6. Therotary electric machine recited in claim 1, wherein a dividing lineextends circumferentially about the axis and through the first andsecond slots, the first and second portions in the first slot beingpositioned on an opposite side of the dividing line from the first andsecond portions in the second slot.
 7. The rotary electric machinerecited in claim 1, wherein the first and second portions have the samenumber of turns.
 8. The rotary electric machine recited in claim 1,wherein the first and second portions have a different number of turns.9. The rotary electric machine recited in claim 1, wherein each of thefirst and second portions has an even number of turns.
 10. The rotaryelectric machine recited in claim 1, wherein each of the first andsecond portions has an odd number of turns.
 11. The rotary electricmachine recited in claim 1, wherein turns of the first portion arestacked radially in the first slot and the second slot.
 12. The rotaryelectric machine recited in claim 11, wherein successive turns of thefirst portion in the first slot are wound in a first radial directionand successive turns of the first portion in the second slot are woundin a second radial direction opposite the first radial direction. 13.The rotary electric machine recited in claim 12, wherein turns of thesecond portion are stacked radially in the first slot and the secondslot.
 14. The rotary electric machine recited in claim 13, whereinsuccessive turns of the second portion in the first slot are wound inthe second radial direction and successive turns of the second portionin the second slot are wound in the first radial direction.
 15. Therotary electric machine recited in claim 1, further comprising a coolingdevice positioned in each of the first and second slots and locatedcircumferentially between the first portion and the second portion. 16.A winding coil for a rotary electric machine having a stator extendingalong an axis and having teeth arranged about the axis, the teeth beingcircumferentially spaced apart by slots, the winding coil comprising: afirst portion for extending through first and second slots of the slotsand including: first end turns extending between the first and secondslots over an axial end surface of the teeth, and a first joint end turncontiguous with the first end turns; and a second portion for extendingthrough the first and second slots and including: second end turnsextending between the first and second slots over the axial end surfaceof the teeth, and a second joint end turn contiguous with the second endturns; the first joint end turn and the second joint end turn beingconnected in series at a joint wherein the first joint end turn and thesecond joint end turn are on an end turn spaced an axial distance closerto the axial end surface than either the first or second end turns. 17.The winding coil recited in claim 16, wherein the joint is positionedaxially between the first and second end turns at a first end of themachine and the first and second end turns at a second end of themachine opposite the first end.
 18. A rotary electric machinecomprising: a stator extending along an axis and having teeth arrangedabout the axis, the teeth being circumferentially spaced apart by slots;and first and second winding coils extending around the teeth andthrough the slots, the first and second winding coils being electricallyconnected to one another to form phases, the first and second windingcoils extending through first and second slots of the slots such thatsuccessive turns of the first winding coil in the first slot are woundin a first radial direction and successive turns of the second windingcoil in the first slot are wound in a second radial direction oppositethe first radial direction.